NestJS中如何为TypeORM实现带请求作用域的依赖注入日志器？

由于TypeORM日志器默认是启动时初始化的单例，无法直接注入NestJS的请求作用域依赖，我们可以通过AsyncLocalStorage(ALS) 传递请求上下文（包括correlationId），同时自定义TypeORM日志器读取ALS中的上下文信息，实现请求级别的日志追踪。

核心思路 #

1. 用ALS存储每个请求的correlationId，确保异步操作中也能访问当前请求的上下文
2. 自定义TypeORM日志器，输出日志时从ALS中获取correlationId并附加到日志内容
3. 通过NestJS拦截器在请求入口处生成并注入correlationId到ALS

具体实现步骤 #

1. 实现AsyncLocalStorage服务 #

创建ALS服务管理请求上下文的存储与读取：

import { Injectable } from '@nestjs/common';
import { AsyncLocalStorage } from 'async_hooks';

@Injectable()
export class AlsService {
  private readonly als = new AsyncLocalStorage<Map<string, any>>();

  // 运行带上下文的回调
  runWithContext<T>(context: Map<string, any>, callback: () => T): T {
    return this.als.run(context, callback);
  }

  // 获取当前上下文
  getContext(): Map<string, any> | undefined {
    return this.als.getStore();
  }

  // 从上下文获取指定键的值
  get(key: string): any {
    const context = this.getContext();
    return context?.get(key);
  }
}

2. 创建请求拦截器注入correlationId #

编写拦截器，在每个请求进来时生成correlationId并存入ALS：

import { Injectable, NestInterceptor, ExecutionContext, CallHandler } from '@nestjs/common';
import { Observable } from 'rxjs';
import { AlsService } from './als.service';
import { v4 as uuidv4 } from 'uuid';

@Injectable()
export class CorrelationIdInterceptor implements NestInterceptor {
  constructor(private readonly alsService: AlsService) {}

  intercept(context: ExecutionContext, next: CallHandler): Observable<any> {
    // 生成唯一correlationId
    const correlationId = uuidv4();
    const contextMap = new Map();
    contextMap.set('correlationId', correlationId);

    // 若需将请求作用域日志器存入ALS，可在此获取并添加
    // const requestLogger = context.switchToHttp().getRequest().logger;
    // contextMap.set('requestLogger', requestLogger);

    // 用ALS包裹请求处理流程
    return this.alsService.runWithContext(contextMap, () => next.handle());
  }
}

3. 自定义TypeORM日志器 #

实现TypeORM的Logger接口，读取ALS中的correlationId并附加到日志：

import { Logger as TypeOrmLogger, QueryRunner } from 'typeorm';
import { Injectable, Logger as NestLogger } from '@nestjs/common';
import { AlsService } from './als.service';

@Injectable()
export class TypeOrmCustomLogger implements TypeOrmLogger {
  constructor(
    private readonly alsService: AlsService,
    private readonly nestLogger: NestLogger,
  ) {}

  private getCorrelatedMessage(message: string): string {
    const correlationId = this.alsService.get('correlationId');
    return correlationId ? `[${correlationId}] ${message}` : message;
  }

  log(message: string, queryRunner?: QueryRunner) {
    this.nestLogger.log(this.getCorrelatedMessage(message));
  }

  error(message: string, trace?: string, queryRunner?: QueryRunner) {
    this.nestLogger.error(this.getCorrelatedMessage(message), trace);
  }

  warn(message: string, queryRunner?: QueryRunner) {
    this.nestLogger.warn(this.getCorrelatedMessage(message));
  }

  debug(message: string, queryRunner?: QueryRunner) {
    this.nestLogger.debug(this.getCorrelatedMessage(message));
  }

  logMigration(message: string, queryRunner?: QueryRunner) {
    this.log(message, queryRunner);
  }

  logQuery(query: string, parameters?: any[], queryRunner?: QueryRunner) {
    const message = `${query} | Parameters: ${JSON.stringify(parameters)}`;
    this.nestLogger.log(this.getCorrelatedMessage(message));
  }

  logQueryError(error: string, query: string, parameters?: any[], queryRunner?: QueryRunner) {
    const message = `${query} | Parameters: ${JSON.stringify(parameters)} | Error: ${error}`;
    this.nestLogger.error(this.getCorrelatedMessage(message));
  }

  logQuerySlow(time: number, query: string, parameters?: any[], queryRunner?: QueryRunner) {
    const message = `Slow query: ${time}ms | ${query} | Parameters: ${JSON.stringify(parameters)}`;
    this.nestLogger.warn(this.getCorrelatedMessage(message));
  }

  logSchemaBuild(message: string, queryRunner?: QueryRunner) {
    this.log(message, queryRunner);
  }
}

4. 配置NestJS模块 #

在根模块中注册ALS服务、拦截器和自定义TypeORM日志器：

import { Module } from '@nestjs/common';
import { TypeOrmModule } from '@nestjs/typeorm';
import { AlsService } from './als.service';
import { CorrelationIdInterceptor } from './correlation-id.interceptor';
import { TypeOrmCustomLogger } from './type-orm-custom.logger';
import { APP_INTERCEPTOR } from '@nestjs/core';

@Module({
  imports: [
    TypeOrmModule.forRootAsync({
      useFactory: (customLogger: TypeOrmCustomLogger) => ({
        type: 'postgres', // 替换为你的数据库类型
        host: 'localhost',
        port: 5432,
        username: 'your-username',
        password: 'your-password',
        database: 'your-db',
        entities: [__dirname + '/**/*.entity{.ts,.js}'],
        synchronize: process.env.NODE_ENV !== 'production',
        logger: customLogger, // 使用自定义日志器
      }),
      inject: [TypeOrmCustomLogger],
    }),
  ],
  providers: [
    AlsService,
    TypeOrmCustomLogger,
    {
      provide: APP_INTERCEPTOR,
      useClass: CorrelationIdInterceptor,
    },
  ],
})
export class AppModule {}

注意事项 #

• 若使用NestJS集群模式，需额外处理ALS的跨worker上下文传递，因为每个worker有独立的ALS实例
• 迁移、Schema构建等非请求上下文的操作不会有correlationId，日志中不会显示该字段，属于正常情况
• 若你的请求作用域日志器有自定义逻辑，可将日志器实例存入ALS，在TypeORM日志器中直接调用该实例的方法，替代单例的NestLogger

内容的提问来源于stack exchange，提问作者Philip Claren